Ensuring partitioned dataset extended (PDSE) critical dataset redundancy (CDR)

Abstract

In one embodiment, a system includes a critical partitioned dataset extended (PDSE) stored to memory of the system; logic adapted for protecting the critical PDSE by creating a copy of the critical PDSE, referred to as a PDSE copy; logic adapted for providing a critical dataset redundancy (CDR) task with exclusive access to the PDSE copy; logic adapted for providing a replacement critical PDSE by redirecting corralled connections to the PDSE copy; logic adapted for protecting the replacement critical PDSE by creating a copy of the replacement critical PDSE, referred to as a replacement PDSE copy; and logic adapted for providing the CDR task with exclusive access to the replacement PDSE copy.

What is claimed is: 
     
       1. A system, comprising:
 a critical partitioned dataset extended (PDSE) stored to memory of the system; 
 logic adapted for protecting the critical PDSE by creating a copy of the critical PDSE, referred to as a PDSE copy; 
 logic adapted for providing a critical dataset redundancy (CDR) task with exclusive access to the PDSE copy; 
 logic adapted for initiating a transaction queue for tracking updates to the critical PDSE; 
 logic adapted for adding any updates performed to the critical PDSE to the transaction queue; 
 logic adapted for updating the PDSE copy according to the transaction queue; 
 logic adapted for quiescing the critical PDSE; 
 logic adapted for corralling a plurality of open connections to the critical PDSE in response to the quiescing; 
 logic adapted for completing each of one or more updates resident in the transaction queue to bring the PDSE copy up to a last known uncorrupted state of the critical PDSE; 
 logic adapted for providing a replacement critical PDSE by redirecting the corralled connections to the PDSE copy; 
 logic adapted for protecting the replacement critical PDSE by creating a copy of the replacement critical PDSE, referred to as a replacement PDSE copy; and 
 logic adapted for providing the CDR task with exclusive access to the replacement PDSE copy. 
 
     
     
       2. The system as recited in  claim 1 , wherein the PDSE copy is a logical equivalent of the critical PDSE and comprises a flag indicating that it is a dataset copy and is accessible only by the CDR task. 
     
     
       3. The system as recited in  claim 2 , further comprising:
 logic adapted for removing the flag from the PDSE copy after providing the replacement critical PDSE; and 
 logic adapted for flagging the replacement PDSE copy to indicate that it is a dataset copy and is accessible only by the CDR task. 
 
     
     
       4. The system as recited in  claim 1 , wherein the system comprises a SMSPDSE server for managing the plurality of open connections to the critical PDSE. 
     
     
       5. The system as recited in  claim 1 , wherein the transaction queue is first-in first-out (FIFO) and is managed exclusively by the CDR task. 
     
     
       6. The system as recited in  claim 1 , wherein the quiescing the critical PDSE occurs at least in part due to detection of corruption in the critical PDSE due to an error. 
     
     
       7. The system as recited in  claim 6 , wherein the error relates to corruption of a PDSE directory for the critical PDSE either in memory of the system or on a direct access storage device (DASD) connected to the system. 
     
     
       8. A computer program product for providing recoverability to a system, the computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising:
 computer readable program code configured for protecting a critical partitioned dataset extended (PDSE) by creating a copy of the critical PDSE, referred to as a PDSE copy; 
 computer readable program code configured for providing a critical dataset redundancy (CDR) task with exclusive access to the PDSE copy; 
 computer readable program code configured for initiating a transaction queue for tracking updates to the critical PDSE; 
 computer readable program code configured for adding any updates performed to the critical PDSE to the transaction queue; 
 computer readable program code configured for updating the PDSE copy according to the transaction queue; 
 computer readable program code configured for quiescing the critical PDSE; 
 computer readable program code configured for corralling a plurality of open connections to the critical PDSE in response to the quiescing; 
 computer readable program code configured for completing each of one or more updates resident in the transaction queue to bring the PDSE copy up to a last known uncorrupted state of the critical PDSE; 
 computer readable program code configured for providing a replacement critical PDSE by redirecting the corralled connections to the PDSE copy; 
 computer readable program code configured for protecting the replacement critical PDSE by creating a copy of the replacement critical PDSE, referred to as a replacement PDSE copy; and 
 computer readable program code configured for providing the CDR task with exclusive access to the replacement PDSE copy. 
 
     
     
       9. The computer program product as recited in  claim 8 , wherein the PDSE copy is a logical equivalent of the critical PDSE and comprises a flag indicating that it is a dataset copy and is accessible only by the CDR task. 
     
     
       10. The computer program product as recited in  claim 9 , further comprising:
 computer readable program code configured for removing the flag from the PDSE copy after providing the replacement critical PDSE; and 
 computer readable program code configured for flagging the replacement PDSE copy to indicate that it is a dataset copy and is accessible only by the CDR task. 
 
     
     
       11. The computer program product as recited in  claim 8 , wherein the system comprises a SMSPDSE server for managing the plurality of open connections to the critical PDSE. 
     
     
       12. The computer program product as recited in  claim 8 , wherein the transaction queue is first-in first-out (FIFO) and is managed exclusively by the CDR task. 
     
     
       13. The computer program product as recited in  claim 8 , wherein the quiescing the critical PDSE occurs at least in part due to detection of corruption in the critical PDSE due to an error. 
     
     
       14. The computer program product as recited in  claim 8 , wherein the error relates to corruption of a PDSE directory for the critical PDSE either in memory of the system or on a direct access storage device (DASD) connected to the system. 
     
     
       15. A computer program product for providing recoverability to a system, the computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising:
 computer readable program code configured for protecting a critical partitioned dataset extended (PDSE) by creating a copy of the critical PDSE, referred to as a PDSE copy, wherein the PDSE copy is a logical equivalent of the critical PDSE; 
 computer readable program code configured for providing a critical dataset redundancy (CDR) task with exclusive access to the PDSE copy; 
 computer readable program code configured for flagging the PDSE copy to indicate that it is a dataset copy and is accessible only by the CDR task; 
 computer readable program code configured for initiating a transaction queue for tracking updates to the critical PDSE: 
 computer readable program code configured for adding any updates performed to the critical PDSE to the transaction queue; 
 computer readable program code configured for updating the PDSE copy according to the transaction queue; 
 computer readable program code configured for quiescing the critical PDSE; 
 computer readable program code configured for corralling a plurality of open connections to the critical PDSE in response to the quiescing, 
 computer readable program code configured for completing each of one or more updates resident in the transaction queue to bring the PDSE copy up to a last known uncorrupted state of the critical PDSE; 
 computer readable program code configured for providing a replacement critical PDSE by redirecting the corralled connections to the PDSE copy; 
 computer readable program code configured for removing the flag from the PDSE copy after providing the replacement critical PDSE; 
 computer readable program code configured for protecting the replacement critical PDSE by creating a copy of the replacement critical PDSE, referred to as a replacement PDSE copy; 
 computer readable program code configured for providing the CDR task with exclusive access to the replacement PDSE copy; and 
 computer readable program code configured for flagging the replacement PDSE copy to indicate that it is a dataset copy and is accessible only by the CDR task.